![]() Normally, breakdown ratings for dielectrics are expressed as a maximum field strength which is basically the ratio of the applied voltage to the dielectric thickness. Capacitor damage or destruction can occur in such situations. This phenomenon, undesirable in most capacitor applications, occurs at the capacitor's breakdown voltage. The dielectric then exhibits dielectric breakdown, or high conductivity in some areas, which tends to lower the stored energy and charge, generating internal heat. ![]() Relative dielectric constants "k" for various dielectricsĪs the charge and voltage on a given capacitor are increased, at some point the dielectric will no longer be able to insulate the charges from each other. It is directly proportional to the " dielectric constant" (Table I) and inversely proportional to the thickness of the dielectric. The capacitance of a device depends mostly on the plate geometry and the nature of the dielectric. The energy stored in a capacitor is the energy required to move the stored charge through the potential of the capacitor. ![]() The ratio of the charge magnitude on each plate to the electric potential (voltage) between the plates is known as capacitance. This situation gives rise to a voltage which increases proportionally with the charge. As the stored charge increases, the electric field across the dielectric increases. The anode and cathode are configured so that very little movement occurs between them as they are charged and the force on the dielectric increases. In order to keep the charges separate, the medium between the anode and cathode, called the dielectric, must be non-conductive an electrical insulator. These charges are generally stored on conductive plates, the positively charged plate called the anode and the negatively charged plate called the cathode (Figure 1). Charges "Q" on anode and cathode induce charges "Q'" on the dielectric.Ĭapacitors store energy as well as charge.
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